They found a sinkhole the right shape and built a radio telescope in it: a 305 metre spherical reflector made of 38,778 perforated aluminium panels, each about 3 by 7 feet, started in September 1960 and opened on 1 November 1963. For fifty-seven years it did radar and radio astronomy, hunted near-Earth objects with NASA and listened for signals from anybody else. Then an auxiliary cable let go on 6 August 2020, a main support cable failed on 7 November, and on 1 December the rest of the cables from one tower went at once and the 900-tonne instrument platform fell through the dish. The NSF said in 2022 it would not be rebuilt. The site is now an education centre, Arecibo C3, and the 12 metre radio telescope and the LIDAR still run. Barrio Esperanza, Arecibo.
Arecibo, Puerto Rico
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